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pick a leader from all the hosts in the inventory (lemmy.world)

submitted 5 months ago by [email protected] to c/[email protected]

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I have an inventory of hosts, and from them, one of the tasks should choose a leader by running a command on each until one of the machines produces an expected output (json value.)

I want some code to run on that leader to initialize it, and then I want some of the other roles to delegate some tasks to that leader.

Not sure how to do this?

Should I use dynamic inventory to analyze a group of hosts, and create a new group (can you run built_in.command in dynamic inventory? Should I write a role task that runs the identifying command on each host, capturing the result globally if it returns what I want (but then running on each host even if I have found my leader?)

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[–] [email protected] 2 points 5 months ago

what you need is a pre_task to query all nodes and get the leader magic bit in a var using register, like below.

- name: Is docker manager
  shell: docker info | grep 'Is Manager'
  register: leader

- name: Get join string
  shell: docker swarm join-token worker
  when: "true in leader.stdout"
  register: token

- name: Join a docker swarm as a worker
  shell: "{{ token.stdout }}"
  when: "true not in leader.stdout"

that is how I would go about getting a docker swarm setup, that any help?